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“Influence of the microstructure on the high-temperature transport properties of GdBaCo2O5.5+\delta epitaxial films”. Burriel M, Casa-Cabanas M, Zapata J, Tan H, Verbeeck J, Solis C, Roqueta J, Skinner SJ, Kilner JA, Van Tendeloo G, Santiso J, Chemistry of materials 22, 5512 (2010). http://doi.org/10.1021/cm101423z
Abstract: Epitaxial thin films of GdBaCo2O5.5+δ (GBCO) grown by pulsed laser deposition have been studied as a function of deposition conditions. The variation in film structure, domain orientation, and microstructure upon deviations in the cation composition have been correlated with the charge transport properties of the films. The epitaxial GBCO films mainly consist of single- and double-perovskite regions that are oriented in different directions depending on the deposition temperature. Additionally, cobalt depletion induces the formation of a high density of stacking defects in the films, consisting of supplementary GdO planes along the c-axis of the material. The presence of such defects progressively reduces the electrical conductivity. The films closer to the stoichiometric composition have shown p-type electronic conductivity at high pO2 with values as high as 800 S/cm at 330 °C in 1 atm O2, and with a pO2 power dependence with an exponent as low as 1/25, consistent with the behavior reported for bulk GBCO. These values place GBCO thin films as a very promising material to be applied as cathodes in intermediate temperature solid oxide fuel cells.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 17
DOI: 10.1021/cm101423z
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“Influence of vibrational states on CO2 splitting by dielectric barrier discharges”. Aerts R, Martens T, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 116, 23257 (2012). http://doi.org/10.1021/jp307525t
Abstract: In this paper, the splitting of CO2 in a pulsed plasma system, such as a dielectric barrier discharge (DBD), is evaluated from a chemical point of view by means of numerical modeling. For this purpose, a chemical reaction set of CO2 in an atmospheric pressure plasma is developed, including the vibrational states of CO2, O2, and CO. The simulated pulses are matched to the conditions of a filament (or microdischarge) and repeated with intervals of 1 μs. The influence of vibrationally excited CO2 as well as other neutral species, ions, and electrons on the CO2 splitting is discussed. Our calculations predict that the electrons have the largest contribution to the CO2 splitting at the conditions under study, by electron impact dissociation. The contribution of vibrationally excited CO2 levels in the splitting of CO2 is found be 6.4%, when only considering one microdischarge pulse and its afterglow, but it can be much higher for consecutive discharge pulses, as is typical for a filamentary DBD, when the interpulse time is short enough and accumulation effects in the vibrationally excited CO2 densities can occur.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 112
DOI: 10.1021/jp307525t
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“Insights in the plasma-assisted growth of carbon nanotubes through atomic scale simulations : effect of electric field”. Neyts EC, van Duin ACT, Bogaerts A, Journal of the American Chemical Society 134, 1256 (2012). http://doi.org/10.1021/ja2096317
Abstract: Carbon nanotubes (CNTs) are nowadays routinely grown in a thermal CVD setup. State-of-the-art plasma-enhanced CVD (PECVD) growth, however, offers advantages over thermal CVD. A lower growth temperature and the growth of aligned freestanding single-walled CNTs (SWNTs) makes the technique very attractive. The atomic scale growth mechanisms of PECVD CNT growth, however, remain currently entirely unexplored. In this contribution, we employed molecular dynamics simulations to focus on the effect of applying an electric field on the SWNT growth process, as one of the effects coming into play in PECVD. Using sufficiently strong fields results in (a) alignment of the growing SWNTs, (b) a better ordering of the carbon network, and (c) a higher growth rate relative to thermal growth rate. We suggest that these effects are due to the small charge transfer occurring in the Ni/C system. These simulations constitute the first study of PECVD growth of SWNTs on the atomic level.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 13.858
Times cited: 56
DOI: 10.1021/ja2096317
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“Investigation of the morphology of the mesoporous SBA-16 and SBA-15 materials”. Stevens WJJ, Lebeau K, Mertens M, Van Tendeloo G, Cool P, Vansant EF, The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical 110, 9183 (2006). http://doi.org/10.1021/jp0548725
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); Electron microscopy for materials research (EMAT)
Impact Factor: 3.177
Times cited: 109
DOI: 10.1021/jp0548725
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“Iron catalysts for the growth of carbon nanofibers : Fe, Fe3C or both?”.He Z, Maurice J-L, Gohier A, Lee CS, Pribat D, Cojocaru CS, Chemistry of materials 23, 5379 (2011). http://doi.org/10.1021/cm202315j
Abstract: Iron is a widely used catalyst for the growth of carbon nanotubes (CNTs) or carbon nanofibers (CNFs) by catalytic chemical vapor deposition. However, both Fe and FeC compounds (generally, Fe3C) have been found to catalyze the growth of CNTs/CNFs, and a comparison study of their respective catalytic activities is still missing. Furthermore, the control of the crystal structure of iron-based catalysts, that is α-Fe or Fe3C, is still a challenge, which not only obscures our understanding of the growth mechanisms of CNTs/CNFs, but also complicates subsequent procedures, such as the removal of catalysts for better industrial applications. Here, we show a partial control of the phase of iron catalysts (α-Fe or Fe3C), obtained by varying the growth temperatures during the synthesis of carbon-based nanofibers/nanotubes in a plasma-enhanced chemical vapor deposition reactor. We also show that the structure of CNFs originating from Fe3C is bamboo-type, while that of CNFs originating from Fe is not. Moreover, we directly compare the growth rates of carbon-based nanofibers/nanotubes during the same experiments and find that CNFs/CNTs grown by α-Fe nanoparticles are longer than CNFs grown from Fe3C nanoparticles. The influence of the type of catalyst on the growth of CNFs is analyzed and the corresponding possible growth mechanisms, based on the different phases of the catalysts, are discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 91
DOI: 10.1021/cm202315j
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“Kinetics of energy selective Cs encapsulation in single-walled carbon nanotubes for damage-free and position-selective doping”. Kato T, Neyts EC, Abiko Y, Akama T, Hatakeyama R, Kaneko T, The journal of physical chemistry: C : nanomaterials and interfaces 119, 11903 (2015). http://doi.org/10.1021/acs.jpcc.5b00300
Abstract: A method has been developed for damage-free cesium (Cs) encapsulation within single-walled carbon nanotubes (SWNTs) with fine position selectivity. Precise energy tuning of Cs-ion irradiation revealed that there is a clear energy window (2060 eV) for the efficient encapsulation of Cs through the hexagonal network of SWNT sidewalls without causing significant damage. This minimum energy threshold of Cs-ion encapsulation (∼20 eV) matches well with the value obtained by ab initio simulation (∼22 eV). Furthermore, position-selective Cs encapsulation was carried out, resulting in the successful formation of pn-junction SWNT thin films with excellent environmental stability.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 3
DOI: 10.1021/acs.jpcc.5b00300
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“A layered iron-rich 2234-type with a mixed valence of iron: the ferrimagnetic Tl-doped Fe2(Sr2-\varepsilonTl\varepsilon)Sr3Fe4O14.65”. Lepoittevin C, Malo S, Nguyen N, Hebert S, Van Tendeloo G, Hervieu M, Chemistry of materials 20, 6468 (2008). http://doi.org/10.1021/cm8014385
Abstract: A new Tl-doped strontium ferrite Fe2(Sr2-Tl)Sr3Fe4O14.65, with an original structure, has been synthesized and structurally characterized by powder X-ray diffraction and transmission electron microscopy. The TGA and Mssbauer studies evidence a mixed valence of iron. The structure exhibits a commensurate modulation, with a F-type subcell a ≈ b ≈ 5.4 Å (≈ ap√2), c ≈ 42 Å with a modulation vector q = αa* with α = 0.4. The supercell parameters have been refined as a= 27.1101(8) Å, b= 5.5187(2) Å and c= 42.0513(9) Å, in the space group Fmmm. The electron diffraction and electron microscopy data of this novel ferrite show that it can be described as a FeTl-2234-type structure corresponding to the intergrowth of a quadruple perovskite slice [(SrFeO2.8)4], with a complex rock salt related slice [Fe2(Sr2-Tl)O3.4]∞, built up of one double iron layer [Fe2O2.4] sandwiched between two [SrO] layers. The HRTEM images show that the oxygen atoms and vacancies are randomly distributed in the perovskite layers while the HAADF STEM images evidence the absence of Tl segregation in the matrix. Fe2(Sr2-Tl)Sr3Fe4O14.65 exhibits a very large value of χ (11emu/mol) at 5 K, which remains large at 400 K; the M(H) loop presents a shape characteristic of ferrimagnetism, with a large coercive field of 0.3 T. The value of magnetization saturates at 400 K at 0.68 μB/Fe. At 10 K, the value of magnetization reaches a maximum of 2 μB/Fe. The resistivity presents a semiconducting-like behavior, with ρ 800 Ω·cm at 300 K.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 8
DOI: 10.1021/cm8014385
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“Leached natural saponite as the silicate source in the synthesis of aluminosilicate hexagonal mesoporous materials”. Linssen T, Cool P, Baroudi M, Cassiers K, Vansant EF, Lebedev O, van Landuyt J, The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical 106, 4470 (2002). http://doi.org/10.1021/jp015578p
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.177
Times cited: 23
DOI: 10.1021/jp015578p
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“Local oxygen-vacancy ordering and twinned octahedral tilting pattern in the Bi0.81Pb0.19FeO2.905 cubic perovskite”. Dachraoui W, Hadermann J, Abakumov AM, Tsirlin AA, Batuk D, Glazyrin K, McCammon C, Dubrovinsky L, Van Tendeloo G, Chemistry of materials 24, 1378 (2012). http://doi.org/10.1021/cm300178x
Abstract: The structure of Bi0.81Pb0.19FeO2.905 was investigated on different length scales using a combination of electron diffraction, high-resolution scanning transmission electron microscopy, synchrotron X-ray powder diffraction, and Mössbauer spectroscopy. In the 80300 K temperature range, the average crystal structure of Bi0.81Pb0.19FeO2.905 is a cubic Pm3̅m perovskite with a = 3.95368(3) Å at T = 300 K. The (Pb2+, Bi3+) cations and O2 anions are randomly displaced along the 110 cubic directions, indicating the steric activity of the lone pair on the Pb2+ and Bi3+ cations and a tilting distortion of the perovskite framework. The charge imbalance induced by the heterovalent Bi3+ → Pb2+ substitution is compensated by the formation of oxygen vacancies preserving the trivalent state of the Fe cations. On a short scale, oxygen vacancies are located in anion-deficient (FeO1.25) layers that are approximately 6 perovskite unit cells apart and transform every sixth layer of the FeO6 octahedra into a layer with a 1:1 mixture of corner-sharing FeO4 tetrahedra and FeO5 tetragonal pyramids. The anion-deficient layers act as twin planes for the octahedral tilting pattern of adjacent perovskite blocks. They effectively randomize the octahedral tilting and prevent the cooperative distortion of the perovskite framework. The disorder in the anion sublattice impedes cooperative interactions of the local dipoles induced by the off-center displacements of the Pb and Bi cations. Magnetic susceptibility measurements evidence the antiferromagnetic ordering in Bi0.81Pb0.19FeO2.905 at low temperatures.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 27
DOI: 10.1021/cm300178x
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“Mechanisms for the trimethylaluminum reaction in aluminum oxide atomic layer deposition on sulfur passivated germanium”. Delabie A, Sioncke S, Rip J, van Elshocht S, Caymax M, Pourtois G, Pierloot K, The journal of physical chemistry: C : nanomaterials and interfaces 115, 17523 (2011). http://doi.org/10.1021/jp206070y
Abstract: Germanium combined with high-κ dielectrics is investigated for the next generations of CMOS devices. Therefore, we study reaction mechanisms for Al2O3 atomic layer deposition on sulfur passivated Ge using calculations based on density functional theory and total reflection X-ray fluorescence (TXRF). TXRF indicates 6 S/nm2 and 4 Al/nm2 after the first TMA/H2O reaction cycle, and growth inhibition from the second reaction cycle on. Calculations are performed on molecular clusters representing −GeSH surface sites. The calculations confirm that the TMA reaction does not affect the S content. On fully SH-terminated Ge, TMA favorably reacts with up to three −GeSH sites, resulting in a near tetrahedral Al coordination. Electron deficient structures with a GeS site shared between two Al atoms are proposed. The impact of the cluster size on the structures and reaction energetics is systematically investigated.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 9
DOI: 10.1021/jp206070y
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“Metal-assisted secondary ion mass spectrometry: the influence of Ag and Au deposition on molecular ion yields”. Adriaensen L, Vangaever F, Gijbels R, Analytical chemistry 76, 6777 (2004). http://doi.org/10.1021/ac049108d
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.32
Times cited: 67
DOI: 10.1021/ac049108d
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“Microprobe speciation analysis of inorganic solids by Fourier transform laser mass spectrometry”. Poels K, van Vaeck L, Gijbels R, Analytical chemistry 70, 504 (1998). http://doi.org/10.1021/ac9709108
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.32
Times cited: 32
DOI: 10.1021/ac9709108
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“Microwave-assisted bromination of double-walled carbon nanotubes”. Colomer J-F, Marega R, Traboulsi H, Meneghetti M, Van Tendeloo G, Bonifazi D, Chemistry of materials 21, 4747 (2009). http://doi.org/10.1021/cm902029m
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 46
DOI: 10.1021/cm902029m
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“Mn(I) in an extended oxide : the synthesis and characterization of La1-xCaxMnO2+\delta (0.6\leq x\leq1)”. Dixon E, Hadermann J, Ramos S, Goodwin AL, Hayward MA, Journal of the American Chemical Society 133, 18397 (2011). http://doi.org/10.1021/ja207616c
Abstract: Reduction of La1xCaxMnO3 (0.6 ≤ x ≤ 1) perovskite phases with sodium hydride yields materials of composition La1xCaxMnO2+δ. The calcium-rich phases (x = 0.9, 1) adopt (La0.9Ca0.1)0.5Mn0.5O disordered rocksalt structures. However local structure analysis using reverse Monte Carlo refinement of models against pair distribution functions obtained from neutron total scattering data reveals lanthanum-rich La1xCaxMnO2+δ (x = 0.6, 0.67, 0.7) phases adopt disordered structures consisting of an intergrowth of sheets of MnO6 octahedra and sheets of MnO4 tetrahedra. X-ray absorption data confirm the presence of Mn(I) centers in La1xCaxMnO2+δ phases with x < 1. Low-temperature neutron diffraction data reveal La1xCaxMnO2+δ (x = 0.6, 0.67, 0.7) phases become antiferromagnetically ordered at low temperature.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 33
DOI: 10.1021/ja207616c
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“Modulated formation of MOF-5 nanoparticles : a SANS analysis”. Nayuk R, Zacher D, Schweins R, Wiktor C, Fischer RA, Van Tendeloo G, Huber K, The journal of physical chemistry: C : nanomaterials and interfaces 116, 6127 (2012). http://doi.org/10.1021/jp3003728
Abstract: MOF-5 nanoparticles were prepared by mixing a solution of [Zn4O(C6H5COO)(6)] with a solution of benzene-1,4-dicarboxylic acid in DMF at ambient conditions. The former species mimics as a secondary building unit (SBU), and the latter acts as linker. Mixing of the two solutions induced the formation of MOF-5 nanoparticles in dilute suspension. The applied conditions were identified as suitable for a closer investigation of the particle formation process by combined light and small angle neutron scattering (SANS). Scattering analysis revealed a significant impact of the molar ratio of the two components in the reaction mixture. Excessive use of the building unit slowed down the process. A similar effect was observed upon addition of 4n-decylbenzoic acid, which is supposed to act as a modulator. The formation mechanism leads to initial intermediates, which turn into cubelike nanoparticles with a diameter of about 60-80 nm. This initial stage is followed by an extended formation period, where nucleation proceeds over hours, leading to an increasing number of nanoparticles with the same final size of 60-80 nm.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 24
DOI: 10.1021/jp3003728
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“Multiple dot-in-rod PbS/CdS heterostructures with high photoluminescence quantum yield in the near-infrared”. Justo Y, Goris B, Sundar Kamal J, Geiregat P, Bals S, Hens Z, Journal of the American Chemical Society 134, 5484 (2012). http://doi.org/10.1021/ja300337d
Abstract: Pb cations in PbS quantum rods made from CdS quantum rods by successive complete cationic exchange reactions are partially re-exchanged for Cd cations. Using STEM-HAADF, we show that this leads to the formation of unique multiple dot-in-rod PbS/CdS heteronanostructures, with a photoluminescence quantum yield of 4555%. We argue that the formation of multiple dot-in-rods is related to the initial polycrystallinity of the PbS quantum rods, where each PbS crystallite transforms in a separate PbS/CdS dot-in-dot. Effective mass modeling indicates that electronic coupling between the different PbS conduction band states is feasible for the multiple dot-in-rod geometries obtained, while the hole states remain largely uncoupled.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 41
DOI: 10.1021/ja300337d
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“New insights into the early stages of nanoparticle electrodeposition”. Ustarroz J, Ke X, Hubin A, Bals S, Terryn H, The journal of physical chemistry: C : nanomaterials and interfaces 116, 2322 (2012). http://doi.org/10.1021/jp210276z
Abstract: Electrodeposition is an increasingly important method to synthesize supported nanoparticles, yet the early stages of electrochemical nanoparticle formation are not perfectly understood. In this paper, the early stages of silver nanoparticle electrodeposition on carbon substrates have been studied by aberration-corrected TEM, using carbon-coated TEM grids as electrochemical electrodes. In this manner we have access to as-deposited nanoparticle size distribution and structural characterization at the atomic scale combined with electrochemical measurements, which represents a breakthrough in a full understanding of the nanoparticle electrodeposition mechanisms. Whereas classical models, based upon characterization at the nanoscale, assume that electrochemical growth is only driven by direct attachment, the results reported hereafter indicate that early nanoparticle growth is mostly driven by nanocluster surface movement and aggregation. Hence, we conclude that electrochemical nulceation and growth models should be revised and that an electrochemical aggregative growth mechanism should be considered in the early stages of nanoparticle electrodeposition.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 104
DOI: 10.1021/jp210276z
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“New mechanism for oxidation of native silicon oxide”. Khalilov U, Pourtois G, Huygh S, van Duin ACT, Neyts EC, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 117, 9819 (2013). http://doi.org/10.1021/jp400433u
Abstract: Continued miniaturization of metal-oxide-semiconductor field-effect transistors (MOSFETs) requires an ever-decreasing thickness of the gate oxide. The structure of ultrathin silicon oxide films, however, critically depends on the oxidation mechanism. Using reactive atomistic simulations, we here demonstrate how the oxidation mechanism in hyperthermal oxidation of such structures may be controlled by the oxidation temperature and the oxidant energy. Specifically, we study the interaction of hyperthermal oxygen with energies of 15 eV with thin SiOx (x ≤ 2) films with a native oxide thickness of about 10 Å. We analyze the oxygen penetration depth probability and compare with results of the hyperthermal oxidation of a bare Si(100){2 × 1} (c-Si) surface. The temperature-dependent oxidation mechanisms are discussed in detail. Our results demonstrate that, at low (i.e., room) temperature, the penetrated oxygen mostly resides in the oxide region rather than at the SiOx|c-Si interface. However, at higher temperatures, starting at around 700 K, oxygen atoms are found to penetrate and to diffuse through the oxide layer followed by reaction at the c-Si boundary. We demonstrate that hyperthermal oxidation resembles thermal oxidation, which can be described by the DealGrove model at high temperatures. Furthermore, defect creation mechanisms that occur during the oxidation process are also analyzed. This study is useful for the fabrication of ultrathin silicon oxide gate oxides for metal-oxide-semiconductor devices as it links parameters that can be straightforwardly controlled in experiment (oxygen temperature, velocity) with the silicon oxide structure.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 24
DOI: 10.1021/jp400433u
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“A new mixed-valence ferrite with a cubic structure, YBaFe4O7: spin-glass-like behavior”. Caignaert V, Abakumov AM, Pelloquin D, Pralong V, Maignan A, Van Tendeloo G, Raveau B, Chemistry of materials 21, 1116 (2009). http://doi.org/10.1021/cm803312f
Abstract: A new mixed-valence ferrite, YBaFe4O7, has been synthesized. Its unique cubic structure, with a = 8.9595(2) Å, is closely related to that of the hexagonal 114 oxides YBaCo4O7 and CaBaFe4O7. It consists of corner-sharing FeO4 tetrahedra, forming triangular and kagome layers parallel to (111)C. In fact, the YBaFe4O7 and CaBaFe4O7 structures can be described as two different ccc and chch close packings of [BaO3]∞ and [O4]∞ layers, respectively, whose tetrahedral cavities are occupied by Fe2+/Fe3+ cations. The local structure of YBaFe4O7 is characterized by a large amount of stacking faults originating from the presence of hexagonal layers in the ccc cubic close-packed YBaFe4O7 structure. In this way, they belong to the large family of spinels and hexagonal ferrites studied for their magnetic properties. Differently from all the ferrites and especially from CaBaFe4O7, which are ferrimagnetic, YBaFe4O7 is an insulating spin glass with Tg = 50 K.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 39
DOI: 10.1021/cm803312f
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“Nitrogen control in nanodiamond produced by detonation shock-wave-assisted synthesis”. Shenderova OA, Vlasov II, Turner S, Van Tendeloo G, Orlinskii SB, Shiryaev AA, Khomich AA, Sulyanov SN, Jelezko F, Wrachtrup J, The journal of physical chemistry: C : nanomaterials and interfaces 115, 14014 (2011). http://doi.org/10.1021/jp202057q
Abstract: Development of efficient production methods of nanodiamond (ND) particles containing substitutional nitrogen and nitrogen-vacancy (NV) complexes remains an important goal in the nanodiamond community. ND synthesized from explosives is generally not among the preferred candidates for imaging applications owing to lack of optically active particles containing NV centers. In this paper, we have systematically studied representative classes of NDs produced by detonation shock wave conversion of different carbon precursor materials, namely, graphite and a graphite/hexogen mixture into ND, as well as ND produced from different combinations of explosives using different cooling methods (wet or dry cooling). We demonstrate that (i) the N content in nanodiamond particles can be controlled through a correct selection of the carbon precursor material (addition of graphite, explosives composition); (ii) particles larger than approximately 20 nm may contain in situ produced optically active NV centers, and (iii) in ND produced from explosives, NV centers are detected only in ND produced by wet synthesis. ND synthesized from a mixture of graphite/explosive contains the largest amount of NV centers formed during synthesis and thus deserves special attention.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 54
DOI: 10.1021/jp202057q
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“Nonlinear optical properties of Ag nanoclusters and nanoparticles dispersed in a glass host”. Mai HH, Kaydashev VE, Tikhomirov VK, Janssens E, Shestakov MV, Meledina M, Turner S, Van Tendeloo G, Moshchalkov VV, Lievens P, The journal of physical chemistry: C : nanomaterials and interfaces 118, 15995 (2014). http://doi.org/10.1021/jp502294u
Abstract: The nonlinear absorption of Ag atomic clusters and nanoparticles dispersed in a transparent oxyfluoride glass host has been studied. The as-prepared glass, containing 0.15 atom % Ag, shows an absorption band in the UV/violet attributed to the presence of amorphous Ag atomic nanoclusters with an average size of 1.2 nm. Upon heat treatment the Ag nanoclusters coalesce into larger nanoparticles that show a surface plasmon absorption band in the visible. Open aperture z-scan experiments using 480 nm nanosecond laser pulses demonstrated nonsaturated and saturated nonlinear absorption with large nonlinear absorption indices for the Ag nanoclusters and nanoparticles, respectively. These properties are promising, e.g., for applications in optical limiting and objects contrast enhancement.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 43
DOI: 10.1021/jp502294u
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“Novel, oxygen-deficient n=3 RP-member Sr3NdFe3O9-\delta and its topotactic derivatives”. Pelloquin D, Hadermann J, Giot M, Caignaert V, Michel C, Hervieu M, Raveau B, Chemistry of materials 16, 1715 (2004). http://doi.org/10.1021/cm030351n
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 24
DOI: 10.1021/cm030351n
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“Numerical study of the size-dependent melting mechanisms of nickel nanoclusters”. Neyts EC, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 113, 2771 (2009)
Abstract: Molecular dynamics simulations were used to investigate the size-dependent melting mechanism of nickel nanoclusters of various sizes. The melting process was monitored by the caloric curve, the overall cluster Lindemann index, and the atomic Lindemann index. Size-dependent melting temperatures were determined, and the correct linear dependence on inverse diameter was recovered. We found that the melting mechanism gradually changes from dynamic coexistence melting to surface melting with increasing cluster size. These findings are of importance in better understanding carbon nanotube growth by catalytic chemical vapor deposition as the phase state of the catalyst nanoparticle codetermines the growth mechanism.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
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“Off-stoichiometry effects on the crystalline and defect structure of hexagonal manganite REMnO3 films (RE = Y, Er, Dy)”. Gélard J, Jehanathan N, Roussel H, Gariglio S, Lebedev OI, Van Tendeloo G, Dubourdieu C, Chemistry of materials 23, 1232 (2011). http://doi.org/10.1021/cm1029358
Abstract: The crystalline and defect structure of epitaxial hexagonal RExMnyO3 (RE = Er, Dy) films with varying cationic composition was investigated by X-ray diffraction and transmission electron microscopy. The films are composed of a strained layer at the interface with the substrate and of a relaxed layer on top of it. The critical thickness is of 10 to 25 nm. For Mn-rich films (or RE deficient), an off-stoichiometric composition maintaining the hexagonal LuMnO3-type structure is stabilized over a large range of the RE/Mn ratio (0.72−1.00), with no Mn-rich secondary phases observed. A linear dependence of the out-of-plane lattice parameter with RE/Mn is observed in this range. Out-of-phase boundary (OPB) extended defects are observed in all films and exhibit a local change in stoichiometry. Such a large solubility limit in the RE deficient region points toward the formation of vacancies on the RE site (RExMnO3−δ, with 0.72 ≤ x < 1), a phenomenon that is encountered in perovskite manganites such as LaxMnO3−δ (x < 1) and that may strongly impact the physical properties of hexagonal manganites.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 17
DOI: 10.1021/cm1029358
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“On the c-Si\mid a-SiO2 interface in hyperthermal Si oxidation at room temperature”. Khalilov U, Pourtois G, van Duin ACT, Neyts EC, The journal of physical chemistry: C : nanomaterials and interfaces 116, 21856 (2012). http://doi.org/10.1021/jp306920p
Abstract: The exact structure and properties of the Si vertical bar SiO2 interface are very important in microelectronics and photovoltaic devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and solar cells. Whereas Si vertical bar SiO2 structures are traditionally produced by thermal oxidation, hyperthermal oxidation shows a number of promising advantages. However, the Si vertical bar SiO2 interface induced in hyperthermal Si oxidation has not been properly investigated yet. Therefore, in this work, the interface morphology and interfacial stresses during hyperthermal oxidation at room temperature are studied using reactive molecular dynamics simulations based on the ReaxFF potential. Interface thickness and roughness, as well as the bond length and bond angle distributions in the interface are discussed and compared with other models developed for the interfaces induced by traditional thermal oxidation. The formation of a compressive stress is observed. This compressive stress, which at the interface amounts about 2 GPa, significantly slows down the inward silica growth. This value is close to the experimental value in the Si vertical bar SiO2 interface obtained in traditional thermal oxidation.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 27
DOI: 10.1021/jp306920p
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“Optimized transport setup for high repetition rate pulse-separated analysis in laser ablation-inductively coupled plasma mass spectrometry”. Lindner H, Autrique D, Garcia CC, Niemax K, Bogaerts A, Analytical chemistry 81, 4241 (2009). http://doi.org/10.1021/ac802627x
Abstract: An optimized laser ablation setup, proposed for high repetition rate inductively coupled plasma mass spectrometry (ICPMS) analyses such as 2D imaging or depth profiling, is presented. For such applications, the particle washout time needs to be as short as possible to allow high laser pulse frequencies for reduced analysis time. Therefore, it is desirable to have an ablation setup that operates as a laminar flow reactor (LFR). A top-down strategy was applied that resulted in the present design. In the first step, a previously applied ablation setup was analyzed on the basis of computational fluid dynamics (CFD) results presented by D. Autrique et al. (Spectrochim. Acta, B 2008, 63, 257−270). By means of CFD simulations, the design was modified in such a way that it operated in the LFR regime. Experimental results demonstrate that the current design can indeed be regarded as an LFR. Furthermore, the operation under LFR conditions allowed some insight into the initial radial concentration distribution if the experimental ICPMS signal and analytical expressions are taken into account. Recommendations for a modified setup for more resilient spatial distributions are given. With the present setup, a washout time of 140 ms has been achieved for a 3% signal area criterion. Therefore, 7 Hz repetition rates can be applied with the present setup. Using elementary formulas of the analytical model, an upper bound for the washout times for similar setups can be predicted. The authors believe that the presented setup geometry comes close to the achievable limit for reliable short washout times.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.32
Times cited: 18
DOI: 10.1021/ac802627x
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“Ordered end-member of ZSM-48 zeolite family”. Kirschhock CEA, Liang D, Van Tendeloo G, Fécant A, Hastoye G, Vanbutsele G, Bats N, Guillon E, Martens JA, Chemistry of materials 21, 371 (2009). http://doi.org/10.1021/cm802614x
Abstract: ZSM-48 and related zeolites are considered to be highly disordered structures. Different polytypes can be clearly distinguished by simulation of high-resolution electron microscopy images. Synthesis of phase-pure polytypes was attempted. One of the investigated samples crystallized via seeding designated as COK-8 consisted of nanoscopic, needlelike crystals with a very large length/width ratio, growing along the pore direction. These specimens are phase-pure polytype 6 (PT6, numbering according to Lobo and van Koningsveld). Aggregates of these nanoneedles occasionally contained a second polytype: PT1. The latter polytype occurred more abundantly in larger crystal rods in an IZM-1 sample crystallized in ethylene glycol. Here too, the isolated crystallites mainly consist of large, defect-free regions of PT6. A simulation of polytype lattice energies offers a rational explanation for the observed polytypical intergrowth formation.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 30
DOI: 10.1021/cm802614x
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“Oxygen vacancy ordering in the double-layered Ruddlesden-Popper cobaltite Sm2BaCo2O7-\delta”. Gillie LJ, Hadermann J, Hervieu M, Maignan A, Martin C, Chemistry of materials 20, 6231 (2008). http://doi.org/10.1021/cm8010138
Abstract: A new oxygen-deficient Ruddlesden−Popper (RP) cobaltite Sm2BaCo2O7−δ (δ ≈ 1.0) has been synthesized and the crystal structure elucidated by Rietveld analysis of X-ray powder diffraction (XRD) data and transmission electron microscopy (TEM). The phase crystallizes in a primitive orthorhombic unit cell, with lattice parameters a = 5.4371(4) Å; b = 5.4405(4) Å and c = 19.8629(6) Å, and space group Pnnm. Contrary to other oxygen-deficient cobalt RP phases, the oxygen vacancies are located in the equatorial positions of the [CoO] layers to give an intralayer structure similar to Sr2Mn2O5, which is not usually observed for cobalt-containing materials. The Sm3+ and Ba2+ cations show a strong preference for distinct sites, with the majority of the larger Ba2+ cations situated in the perovskite block layers and Sm3+ cations predominantly in the rock salt layers. Magnetic susceptibility data demonstrate the strong antiferromagnetic (AFM) character of Sm2BaCo2O7−δ.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 7
DOI: 10.1021/cm8010138
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“Physicochemical and structural characterization of mesoporous aluminosilicates synthesized from leached saponite with additional aluminum incorporation”. Linssen T, Cassiers K, Cool P, Lebedev O, Whittaker A, Vansant EF, Chemistry of materials 15, 4863 (2003). http://doi.org/10.1021/cm031111a
Abstract: A thorough investigation was performed on the physical (mechanical, thermal, and hydrothermal stability) and chemical (ion exchange capacity and silanol number) characteristics of aluminosilicate FSMs, synthesized via a new successful short-time synthesis route using leached saponite and a low concentration of CTAB. Moreover, the influence of an additional Al incorporation, utilizing different aluminum sources, on the structure of the FSM derived from saponite is studied. A mesoporous aluminosilicate with a low Si/Al ratio of 12.8 is synthesized, and still has a very large surface area of 1130 m(2)/g and pore volume of 0.92 cm(3)/g. The aluminum-containing samples all have a high cation exchange capacity of around 1 mmol/9 while they still have a silanol number of about 0.9 OH/nm(2); both characteristics being interesting for high-yield postsynthesis modification reactions. Finally, a study is performed on the transformation of the aluminosilicates into their Bronsted acid form via the exchange with ammonium ions and a consecutive heat treatment.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 9.466
Times cited: 11
DOI: 10.1021/cm031111a
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“Plasma-based dry reforming : a computational study ranging from the nanoseconds to seconds time scale”. Snoeckx R, Aerts R, Tu X, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 117, 4957 (2013). http://doi.org/10.1021/jp311912b
Abstract: We present a computational study for the conversion of CH4 and CO2 into value-added chemicals, i.e., the so-called dry reforming of methane, in a dielectric barrier discharge reactor. A zero-dimensional chemical kinetics model is applied to study the plasma chemistry in a 1:1 CH4/CO2 mixture. The calculations are first performed for one microdischarge pulse and its afterglow, to study in detail the chemical pathways of the conversion. Subsequently, long time-scale simulations are carried out, corresponding to real residence times in the plasma, assuming a large number of consecutive microdischarge pulses, to mimic the conditions of the filamentary discharge regime in a dielectric barrier discharge (DBD) reactor. The conversion of CH4 and CO2 as well as the selectivity of the formed products and the energy cost and energy efficiency of the process are calculated and compared to experiments for a range of different powers and gas flows, and reasonable agreement is reached.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 118
DOI: 10.1021/jp311912b
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